Wavelength-selective metamaterial absorbers in the mid-infrared range are demonstrated by using multiple tungsten cross resonators. By adjusting the geometrical parameters of cross resonators in single-sized unit cells, near-perfect absorption with single absorption peak tunable from 3.5 μm to 5.5 μm is realized. The combination of two, three, or four cross resonators of different sizes in one unit cell enables broadband near-perfect absorption at mid-infrared range. The obtained absorption spectra exhibit omnidirectiona lity and weak dependence on incident polarization. The underlying mechanism of near-perfect absorption with cross resonators is further explained by the optical mode analysis, dispersion relation and equivalent RLCmore » circuit model. Furthermore, thermal analysis is performed to study the heat generation and temperature increase in the cross resonator absorbers, while the energy conversion efficiency is calculated for the thermophotovolta ic system made of the cross resonator thermal emitters and low-bandgap semiconductors.« less

A method is suggested of efficient mid- to far-infrared (ir) pulse amplification via driving optical pulse energy conversion in waveguiding quantum well (QW) heterostructures at room temperature. It is based on the optical pulse creating transient population inversion at a long-wavelength transition in the three-level scheme formed by QW levels of dimensional quantization. As a result, efficient amplification of a weak mid- to far-ir pulse, propagating simultaneously with the driving one, becomes possible. A waveguide and QW heterostructure design that is optimal for optical-long-wavelength pulse conversion is proposed and shown to be much simpler than that used in quantum cascademore » lasers. For the typical input peak power of a picosecond driving pulse and mid- to far-ir pulse of {approx}100 W and 100-0.1 mW, respectively, the present scheme is able to produce output ir pulses with peak powers of at least several tens of watts or several tens of milliwatts in the mid- or far-ir range, respectively, i.e., to convert an appreciable part of the optical pulse energy into the mid-ir signal.« less

Silicon-on-nitride (SON) is a convenient, low-loss platform for mid-infrared group IV plasmonics and photonics. We have designed 5-layer SON channel-waveguides and slab-waveguides for the 2.0 to 5.4 μm wavelength range and have simulated the resulting three-dimensional (3D) and two-dimensional (2D) SON gap-plasmon modes. Our simulations show propagation lengths of ∼60 μm for 3D gap-strip modes having a 0.003 λ{sup 2} cross-section. Because the ∼50-nm SON (Si{sub 3}N{sub 4}) mode region is also a gate insulator between silver (Ag) and n-doped Silicon (Si), metal-oxide-semiconductor accumulation gating is available for electro-optical loss modulation of the gap-confined mode.